Feb

27

The study’s conclusions may disappoint the many Americans who take garlic and garlic supplements in hopes of controlling high cholesterol levels linked to heart disease.

They’re wasting their money, said Christopher Gardner, a nutrition scientist at the Stanford Prevention Research Center and a senior author of the study.

“It works in a test tube, on cells. In rats, it works,” Gardner said. “In humans, nothing. We are very disappointed with the results, but it was an excellently done study.”

A number of previous studies in people have shown that an active ingredient in garlic, allicin, can reduce cholesterol levels, but many were sponsored by supplement makers. Others were conducted using poor methodology, making their conclusions suspect, Gardner said.

A federal government-commissioned review of 1,800 studies on the health benefits of garlic found that while studies lasting less three months showed an improvement in cholesterol levels, longer studies did not. Still, garlic supplements remain popular, with U.S. sales now topping $150 million a year.

The Stanford researchers say their study is the first independently conducted, long-term study to examine whether both raw garlic and garlic supplements can reduce cholesterol in people with moderately high cholesterol. The $1.5 million study, sponsored by the National Institutes of Health, was published in Monday’s issue of the Archives of Internal Medicine.

An editorial accompanying the study noted that “the jury is still out” on whether garlic can improve overall heart health, even if it doesn’t lower cholesterol.

Too much LDL cholesterol, the “bad” cholesterol, can increase the risk of heart disease, and patients are encouraged to lower it through diet, exercise and medication. The 192 participants in the study had cholesterol levels high enough to merit trying diet or exercise to lower them, but not to require cholesterol-lowering prescription medication.

The researchers gave the subjects either raw garlic, Garlicin-powdered garlic, Kyolic-aged garlic or a placebo six days a week for six months. Raw garlic was added to condiments for the more than 30,000 sandwiches made for the study. The participants ate the equivalent of a clove of garlic each day, a bit more than a standard garlic supplement pill.

Alan Kornfield was surprised to find out he had been given placebos during the study, and dismayed by the study’s overall results.

“I’m really, really disappointed, because we love garlic,” said the 47-year-old San Mateo man who, with his wife, often adds garlic to whatever they’re eating and is now using the drug Lipitor to control his cholesterol. “I was hoping to do anything to avoid prescription drugs.”

Researchers monitored everyone in the study to make sure they didn’t gain or lose weight, which can affect cholesterol levels, and Gardner said the subjects didn’t significantly change their exercise or diet habits. In monthly checks, researchers found that the participants’ levels of LDL cholesterol remained nearly constant throughout the study.

An Archives of Internal Medicine editorial accompanying the study said that while the results “convincingly” demonstrated that garlic does not significantly lower LDL cholesterol, they do not prove that garlic is useless in preventing heart disease.

That point was echoed by Daniel Fabricant, vice president of scientific affairs for the Natural Products Association, a trade group. Fabricant acknowledged that the study appeared to be well-designed, but was troubled that it was presented as the last word on the issue.

“We know there’s some biological effect,” he said.

Garlic’s potential for improving heart health was first recorded about 3,500 years ago in Egypt, and Western researchers have been studying its medicinal qualities for two centuries.

Garlic may have other disease-fighting properties that should be studied further ? it seems to lower blood pressure, for example ? but reducing cholesterol isn’t one of them, Gardner said.

Still, there were some study participants who simply didn’t believe the results, he said.

“They were such zealots,” Gardner said. “They were going to keep taking it.”